A case of pregnancy following a modified Strassman procedure applied to treat a placental site trophoblastic tumour
Dr S Saso, Division of Surgery and Cancer, Institute of Reproductive and Developmental Biology, Imperial College London, Hammersmith Hospital Campus, Du Cane Road, London, W12 0NN, UK. Email firstname.lastname@example.org
Please cite this paper as: Saso S, Chatterjee J, Yazbek J, Thum Y, Keefe K, Abdallah Y, Naji O, Lindsay I, Savage P, Seckl M, Smith J. A case of pregnancy following a modified Strassman procedure applied to treat a placental site trophoblastic tumour. BJOG 2012; DOI: 10.1111/j.1471-0528.2012.03501.x.
We present the first case of a term pregnancy following a fertility-preserving procedure (modified Strassman procedure; MSP) to treat a placental site trophoblastic tumour (PSTT). The woman has given written permission for the case to be reported. A 34-year-old white British woman presented in August 2006 as a nulliparous female with an elevated human chorionic gonadotrophin (β-hCG; 350 000 iu) following a scan at 11 weeks of gestation which diagnosed a molar pregnancy. She had no previous medical history or personal or family history of gestational trophoblastic disease (GTD). After uterine evacuation β-hCG was 16 000 iu. Histology of the evacuated tissue was consistent with a partial mole. Doppler ultrasonography showed a 3.7-cm round, mixed echogenic mass lying centrally within the uterine fundus, with increased vascularity at the periphery. The right ovary contained a dermoid cyst and the left ovary was normal. A chest X-ray showed no metastases. She was commenced on ‘low-risk’ chemotherapy treatment (methotrexate) a month later, which rapidly decreased the β-hCG levels as well as the size of the lesion. A second course of chemotherapy (‘high-risk’) followed in 2007 secondary to a relapse, with β-hCG levels normalising within 2 months. Unfortunately she relapsed for the second time in May 2008. An ultrasound scan revealed a lesion that was 1.2 cm in size, of abnormal vascularity and reduced Doppler flow and just to the right of the midline. Magnetic resonance imaging confirmed a 1.2-cm focus in the anterior uterine fundus. Following a hysteroscopy and use of a resectoscope, histology revealed that the focus was consistent with a PSTT, with one margin involved in the trophoblastic tumour itself. Subsequently, the lesion was resected using MSP, with uterine reconstruction. Intraoperative ultrasound with aqua flotation was applied to locate the tumour before making the necessary excision. All lymph nodes (34 in total) were tumour free. Clear histological margins were demonstrated on frozen section.
Modified Strassman procedure has been described extensively in a previous BJOG publication by Saso et al.1 Below is a summary of the procedure as undergone by the woman reported here. She had given consent for a low transverse muscle-cutting laparotomy with MSP and pelvic/para-aortic lymph node sampling. A low transverse muscle-cutting incision was used with ligation of the inferior epigastric vessels. On entering the abdomen a normal-sized uterus was seen and the placental nodule was palpable deep within the uterus at the site shown on the scan. The free peritoneal fluid was sucked up and sent for cytopathology. The left ovary had a small haemorrhagic cyst. The right ovary had some minor adhesions, which released. Following opening of the broad ligaments, a Foley catheter was placed around the uterine vessels to temporarily occlude the uterine arterial supply, so permitting uterine isolation. This involves feeding the catheter under the round ligament through perforations created in the peritoneum. Diathermy and transillumination allowed for avoidance of vessels. This effect was enhanced by the placement of bulldog clips on the ovarian ligaments. The ovarian ligaments universally contain one artery and two veins; the clips were removed intermittently during the procedure to ensure that a hypoxic insult did not affect the ovaries, notwithstanding the fact that the clips were placed between the ovaries and the uterus. The length of time that the uterus was isolated from its blood supply was also noted. The external iliac, internal iliac and obturator lymph nodes were all sampled. A muscle-cutting approach was used to allow for lymph node sampling.
The tumour was subsequently identified and following use of a ‘cold knife’, an incision was made at a distance of 1 cm from the lesion. This incision is generally full thickness through to the uterine cavity and may even involve hemisection of the uterus. This allows excision with a margin around the nodule. At the end of this part of the procedure, the sling was removed. The authors have not experienced any problems with this technique when used for up to 1 hour.
The uterus was reconstructed, using a number of different suture materials for the respective uterine layers: vicryl 3-0 to the endometrium, vicryl 2-0 to the myometrium and PDS 3-0 to the serosa. At the end of the procedure, Robinson and Redivac drains were placed into the pelvis and under the rectus sheath, respectively. Surgicel was inserted across the uterus and on both pelvic side walls. The abdomen was closed using Vicryl to peritoneum, looped PDS to sheath and clips to skin.
Postoperative recovery was uneventful. Regular menses were reported by the woman a year after surgery, allowing us to assume that her reproductive function had returned to normal. This was confirmed by subsequent pregnancies. She miscarried once (at 7 weeks of gestation) in 2009, followed by a termination of pregnancy later in the year, at 17 weeks secondary to trisomy 21. However, the third pregnancy post-MSP resulted in a symmetrically well-grown, healthy, term baby, weighing 3.2 kg and delivered via caesarean section at 38 weeks. The placenta was not adherent to the MSP scar, conception was natural, and the gestational and interpartum periods were uneventful.
Placental site trophoblastic tumour is an atypical variant of GTD. Named in 1981, it is a slow-growing malignant neoplasm that can occur following a full-term delivery, miscarriage or a hydatidiform molar pregnancy. The time from the index pregnancy to diagnosis can vary from a few months to several years.2 It differs from other GTD types because of its characteristically low β-hCG levels, late-onset aggressive nature, slow growth, random malignant potential and relative resistance to standard chemotherapeutic regimens.3
The management of PSTT is still open to debate with current guidelines alternating between chemotherapy, surgery and a combination of both. This may be attributed to the rarity of PSTT, its primary effect on women of childbearing age and unpredictable biological behaviour, as well as reduced chemosensitivity.4 The delay in childbearing in the developed word has highlighted fertility preservation as an essential factor to be discussed with the women diagnosed with this condition. The MSP is a fertility-preserving surgery, which when applied to treat a PSTT, involves localised tumour resection followed by uterine reconstruction. If a woman wants to preserve her fertility then MSP should be discussed with her, especially as a PSTT is typically less sensitive to chemotherapy.1 This procedure has already been employed in the management of a giant adenomatoid tumour of the uterus.5
Saso et al.1 presented five women who underwent MSP to treat a presumed solitary uterine PSTT. Following surgery, all women remained in remission. Only one has remained in remission with her fertility intact (case reported here). The other four underwent a completion hysterectomy because of possible incomplete excision of the disease. No residual disease was later found in two of these four uteri.4 Since then, the sole woman who had her fertility preserved has delivered a healthy, term baby. Furthermore, another woman has undergone an MSP to treat a PSTT. She is also in remission without requiring a subsequent completion hysterectomy.
This report of pregnancy post-MSP strengthens our conclusion from Saso et al.1 that ‘…fertility-preserving surgery could be a necessary addition when counselling a woman with PSTT regarding her treatment options in the case of presumed unifocal disease’.1 The resistance to chemotherapy of PSTTs when compared with other forms of GTD means that surgical management is the primary option. A total abdominal hysterectomy and routine pelvic and retroperitoneal lymph node sampling is the procedure of choice. Our belief is that a subgroup of carefully selected women diagnosed with a unifocal, localised PSTT and wishing to preserve their fertility should be offered an MSP.
Therefore, an MSP can be added to the ever-growing list of gynaecological surgical procedures that are both curative and fertility preserving. Examples include the use of both vaginal and abdominal radical trachelectomies to treat early stage cervical cancer diagnosed in women wishing to maintain their fertility. The idea of abdominal radical trachelectomies in particular has demonstrated that the uterus is capable of sustaining a term pregnancy with only the ovarian vessels within the vascular pedicles intact.6 Other cases described involve the first case of fertility-sparing surgery for a giant adenomatoid tumour of the uterus (a tumour previously managed by hysterectomy),5 a successful cessation of haemorrhage in a woman with a ruptured cornual ectopic pregnancy without recourse to hysterectomy,7 and the surgical management of uterine arteriovenous malformation where selective temporary ligation of the uterine and ovarian vessels was applied.8
From our cohort, all six women are still in remission, with the last two not requiring a completion hysterectomy, resulting in preserved fertility. The fifth woman had the pregnancy reported here. We recognise that our cohort is limited and more data are required so we are unable to generalise the findings. However the application of frozen section intraoperatively following cold knife dissection rather than electrodiathermy of biopsies and their immediate analysis by a highly experienced GTD pathologist, together with the novel use of intraoperative ultrasound under aqua flotation, may allow us to offer women a much improved prognosis in the future. This change in treatment was applied for the last two women as a potential solution in preventing completion hysterectomies post-MSP which was the case for the first four.
Fertility-sparing options must be highlighted in a woman presenting with PSTT because this unique form of GTD primarily occurs in women of reproductive age. The woman’s ultimate decision should be her own, made independently following appropriate counselling and consultation with her family. Our hope is that our novel diagnostic technique of using intraoperative frozen section with cold knife dissection will lead to a decrease in the incidence of completion hysterectomy following MSP and will increase the chance of future pregnancies. The knowledge that the purpose of an MSP had been to maintain their fertility seemed psychologically helpful, even to those women who had a completion hysterectomy.
Disclosure of interest
None to declare.
Contribution to authorship
SS was responsible for the original manuscript design and draft, and data collection. JC, KWK, YA and ON were responsible for drafting and revision for important intellectual content. JY introduced the idea of using intraoperative ultrasound under aqua flotation for diagnostic purposes. YT is a fertility specialist who was responsible for consulting the team with respect to conception and implantation issues. IL was the pathologist who reviewed the PSTT samples. MJS and PMS were responsible for providing important intellectual content throughout the manuscript’s production, drafting parts of the manuscript, and for final approval of the version to be published. JRS is the guarantor for this paper and accepts full responsibility for the work and the conduct of the study. His involvement was critical to every phase of this work and he controlled the decision to publish. He was also the chief gynaecological surgeon who applied MSP to treat PSTT at our institution.
Details of ethics approval
The woman has given written permission for the case to be reported.